Mouthpiece



FIG. 1 is a perspective view of a mouthpiece from the side, showing my design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines which define the bounds of the claimed design form no part thereof. 

The ornamental design for a mouthpiece, as shown and described. 